This invention provides polyester thermosetting resin compositions and products obtained from formulations containing such compositions, in which the polyester is chemically modified by reaction with organosilicone thermosetting compounds, in particular, organosilicone thermosetting elastomers.
More particularly, the invention provides polyester thermosetting resin "dough" moulding compositions wherein a "dough" comprising the chemically modified polyester thermosetting resin composition, catalyst, fillers and additives can be formed to shape in hot dies under high pressure, although in other embodiments the chemically modified polyester may include thermosetting resin compositions which are suitable for extruding, pultruding and hand lay-up processes and injection, compression and transfer moulding by appropriate changes therein.
In the past it has been suggested to add silicone prepolymers to certain thermoplastic materials and reference may be made to the publication "Plastics Technology", August 1985, pp 57-61. This publication describes the interpenetrating polymer networks which develop when a silicone prepolymer is admixed with a thermoplastic resin.
No prior art is known which describes the cross-linking by free radical or siloxane hydride to unsaturated bond reactions of heat-curable thermosetting organo-silicone compounds, in particular, organo-silicone thermosetting elastomer materials, into unsaturated polyester resins to form heat-curable cross-linked polyester thermosetting resins. By "thermosetting" is meant a polymeric composition capable of being cured or cross-linked so that it cannot be re-melted without destroying its chemical nature. Thermosets are characterized by the presence of extensive primary covalent bonds between molecules, in distinction to the weak secondary intermolecular forces characteristic of the re-meltable thermoplastic polymers.